But watching the diminutive scrum-half run, pass, tackle – and how does he like a tackle – against England on Saturday, your preconceptions are banished and erased.

The 5’10” Connacht scrumhalf may not be Conor Murray, but he never said he would be. He’s Kieran Marmion, plays like him and wants to be the best Kieran Marmion there can be.

On Saturday’s showing, against the world’s in-form team, his was a towering performance given the context. This was his first Six Nations start, with two days’ notice, and up against a side chasing an unprecedented 19th win in a row.

“It’s given me a taste of the big time, for sure,” Marmion said after the game, with a red battle scar skating halfway down the right side of his face an instant confirmation that this was, indeed, “the big time”.

“Those kind of experiences are pretty valuable. You can really take a lot out of them to know that you’ve played against the second best team in the world, at the moment. You can take a lot away from that and just build.”

Now 25, Marmion is not quite the young buck he appears, but with Conor Murray so central to Joe Schmidt’s plans, regular game time has been hard to come by with the national side.

Saturday helped hugely. He ghosted around the pitch, passing sharply and quickly, and gave another physical performance - as he did on the wing against Australia in November, proving that what might be lacking in bulk is made up for in bravery.

A first half trip on the flying Elliot Daly was a keeper. “I guess he just caught my eyeline pretty late and I just had to dive out and try to get him,” he said.

Given his relatively short time playing alongside Johnny Sexton, it was unlikely to be as perfect a partnership as the potential Lions’ duo of the Leinster star and Murray, but it wasn’t a bad audition.

“I was under no illusion it would be tough,” he said, “obviously Conor has performed so well the last few years, I knew I had a lot to try and live up to. Throughout the week a lot of lads gave me confidence in training, kept telling me to nail what I have to do. Conor was there for me as well ... anything I had to ask he was there to help me out.”

Having faced South Africa in Johannesburg, Wales in Cardiff and New Zealand in Dublin, Marmion didn’t come into the game totally raw, but Saturday took things to a new level.

“Was it the toughest game I’ve played in? Probably,” he said. “You know when you’re going to get hit. There’s a step up in pace as well, it’s a big change, you’re blowing a lot harder and you just have to fight through that. It was pretty tough out there, tough conditions as well.”

There were obvious lessons learned, and some not so obvious to observers in the stands.

“I knew they would probably be trying to put me and Johnny under pressure, and I could definitely hear them at all the rucks and stuff, giving me a good bit of verbal pressure,” Marmion said. “You can hear them shouting, ‘I’m all over him, I’ve got him.’ I guess it’s just a way of putting people off and you just have to try and block that out.”

With Murray likely to be the only Ireland scrum half touring with the Lions this summer, Marmion’s eyes are on the US and Japan where he hopes to show Joe Schmidt more of what he’s got in the locker.

“I’m always trying as best I can to put [Murray] under pressure but he is obviously so good at the moment,” he said. “I can’t live in awe of him, so I’ll try to put as much pressure on as I can to perform as best I can.